The invention herein relates to jointed assemblies in which one member is moved relative to another by means of hydraulic or pneumatic power. Such assemblies include, for example, automatically opening doors, robotic limbs or any assembly where hydraulic or pneumatic cylinders effect mechanical movement between parts.
The invention is a jointed assembly actuated by a mechanical muscle. The muscle includes a longitudinally inflexible but radially or circumferentially expandable sleeve surrounding a pressurizable bladder of elastic material. The bladder expands when pressurized and bulges the wall of the sleeve outward, whereby the sleeve contracts axially to compensate for length taken up by the sleeve's bulge. Terminus means at either end of the sleeve connect the sleeve to different components of the jointed assembly so that the sleeve's axial contraction effects relative movement between the components.